ECONOMIC ECONOMIC IMPORTANCE OF IMPORTANCE OF COWPEA WEEVILCOWPEA WEEVIL

BY:BY:JACKSON NYARKOJACKSON NYARKO,,

MPHIL (ENTOMOLOGY)MPHIL (ENTOMOLOGY)

SCOPESCOPE INTRODUCTIONINTRODUCTION THE COWPEATHE COWPEA THE COWPEA WEEVILTHE COWPEA WEEVIL IMPORTANCE OF BEAN BEETLEIMPORTANCE OF BEAN BEETLE CONCLUSIONCONCLUSION

INTRODUCTIONINTRODUCTION Sep. 27, 2010 Sep. 27, 2010 — A long neglected crop — A long neglected crop

with the potential to halt hunger for with the potential to halt hunger for millions in Africa, sustain the livestock millions in Africa, sustain the livestock revolution underway in developing revolution underway in developing countries, rejuvenate nutrient-sapped soils, countries, rejuvenate nutrient-sapped soils, and even feed astronauts on extended and even feed astronauts on extended space missions, is attracting scientists from space missions, is attracting scientists from around the world to Senegal this week for around the world to Senegal this week for the Fifth World Cowpea Research the Fifth World Cowpea Research Conference.Conference.

- Science Daily, 2010- Science Daily, 2010

INTRODUCTIONINTRODUCTION

Economic importance of cowpea Economic importance of cowpea weevil, pest of cowpea: weevil, pest of cowpea: reference to its impact on the reference to its impact on the cowpeacowpea

Significance of this impact: Significance of this impact: related to the economic value of related to the economic value of the cowpeathe cowpea

Thus the impact of the economic Thus the impact of the economic loss of the cowpea by the pest loss of the cowpea by the pest is much appreciated.is much appreciated.

THE COWPEA,THE COWPEA,Vigna unguiculata Vigna unguiculata (L) Walp(L) Walp

About 150-190 spp in the family About 150-190 spp in the family FabaceaeFabaceae

Common: Common: V. radiata V. radiata (mung/green bean); (mung/green bean); V. subterranea V. subterranea (bambara groundnut); (bambara groundnut); V. V. angularis angularis (red bean/azuki); (red bean/azuki); V. V. unguiculalataunguiculalata, 4 ssp., 4 ssp.

Important: Important: V. unguiculata V. unguiculata sspssp. Unguiculat . Unguiculat (black-eyed pea, southern cowpea(black-eyed pea, southern cowpea

Clockwise: red beans, black eyed Clockwise: red beans, black eyed peas (cowpeas) and mung beanspeas (cowpeas) and mung beans

Photo © Beck and Blumer, 2011

mapsmaps

Sub-Saharan Africa

Ghana

Origin and DistributionOrigin and Distribution

Pan-tropical distributionPan-tropical distribution Originated in Africa about 5-6 Originated in Africa about 5-6 tya (Davis et al, 1991)tya (Davis et al, 1991)

Now grown in:Now grown in:⁄ Western and Central – SSA Western and Central – SSA (important)(important)

⁄ Latin AmericaLatin America⁄ Southeast AsiaSoutheast Asia⁄ Southern United StateSouthern United State

How Important is Cowpea?How Important is Cowpea?

The second most important legume The second most important legume after groundnut – esp. in Ghanaafter groundnut – esp. in Ghana

Source of protein to most homesSource of protein to most homes Provide to humans – Provide to humans – Animal feed – from leaves, stalksAnimal feed – from leaves, stalks Sold for cash income by millions of Sold for cash income by millions of African families – <60% is stored African families – <60% is stored and sold when prices go up in off-and sold when prices go up in off-season (IITA, 2010)season (IITA, 2010)

Annual global production: aprx. Annual global production: aprx. 3.3m tons3.3m tons

How Important is Cowpea?How Important is Cowpea? Many cultivars of various economic Many cultivars of various economic values developed – IITA, CSIR-SARI, values developed – IITA, CSIR-SARI, CGAIR, etcCGAIR, etc

Well adapted to harsh, arid Well adapted to harsh, arid climates, and poor soilclimates, and poor soil

Will survive threats of climate Will survive threats of climate change better than maize and rice change better than maize and rice (Science Daily, 2010)(Science Daily, 2010)

Nitrogen fixing ability – enriches Nitrogen fixing ability – enriches soil, crop rotationsoil, crop rotation

Very vulnerable to pests (bruchid) – Very vulnerable to pests (bruchid) – field through marketfield through market

THE COWPEA WEEVILTHE COWPEA WEEVILCallosobruchus maculatusCallosobruchus maculatus Fabricius Fabricius

Not a true weevil; properly called Not a true weevil; properly called bean beetlebean beetle

Coleoptera: Chrysomelidae: Coleoptera: Chrysomelidae: Bruchinae (Beck and Blumer, 2011; Bruchinae (Beck and Blumer, 2011; PaDIL)PaDIL)

Common pest of stored legumes, Common pest of stored legumes, preferably cowpea – so-called preferably cowpea – so-called cowpea weevil or bean beetlecowpea weevil or bean beetle

Sexually dimorphic Sexually dimorphic

Origin and DistributionOrigin and Distribution

Originated in West Africa – moved Originated in West Africa – moved around the globe with the trade around the globe with the trade of legumes and other cropsof legumes and other crops

Cosmopolitan distribution – Cosmopolitan distribution – occurring everywhere except occurring everywhere except AntarcticaAntarctica

Faced bottlenecks but has Faced bottlenecks but has prevailed as a pest because of prevailed as a pest because of its ability to withstand its ability to withstand inbreedinginbreeding

Host Preference Host Preference

Larvae develops exclusively Larvae develops exclusively inside cowpea seedinside cowpea seed

Female may lay 70-100 eggs; Female may lay 70-100 eggs; preferably on large seeds, preferably on large seeds, smooth seed coat surfacesmooth seed coat surface

Oviposition usually 1:1, Oviposition usually 1:1, especially when choice beans especially when choice beans are abundantare abundant??????

Develops in wide range of Develops in wide range of temperatures and humiditytemperatures and humidity

IMPORTANCE OF BEAN IMPORTANCE OF BEAN BEETLEBEETLE ResearchResearch DamageDamage Economic lossesEconomic losses Control Control Recovery Recovery

Model organism for Model organism for research and educationresearch and education Quick generation time – 4-8 Quick generation time – 4-8 days; 3-7 weeks; 24-36 hrs; days; 3-7 weeks; 24-36 hrs; 10-14 days (Beck and Blumer, 10-14 days (Beck and Blumer, 2011)2011)

Sexual dimorphismSexual dimorphism Ease of maintenanceEase of maintenance

Damage to cowpeaDamage to cowpea Larva eats Larva eats endosperm and endosperm and embryo of seed embryo of seed

Bean becomes Bean becomes hollow – resulting hollow – resulting in weight loss. in weight loss.

Adult emerges by Adult emerges by chewing and making chewing and making an emergence holean emergence hole

Reported economic Reported economic losseslosses

A single beetle A single beetle can cause 3.5% can cause 3.5% wt losswt loss

Loss of food Loss of food quantity and quantity and quality: e.g. quality: e.g.

⁄ mean fat content = mean fat content = 2.75:6.23; 2.75:6.23;

⁄ mean crude mean crude protein=14.90:50:50; protein=14.90:50:50;

⁄ mean mean carbohydrate=21.74:5.87 carbohydrate=21.74:5.87 (Oke & Akintunde, 2013)(Oke & Akintunde, 2013)

Overall cowpea Overall cowpea lossloss

⁄ Up to 50%, Africa Up to 50%, Africa annually (annually (www.gatesfoundation.org, 2010), 2010)

⁄ 50-90% across Africa 50-90% across Africa (IITA,1989)(IITA,1989)

⁄ 70% seed infestation, 70% seed infestation, 30% wt loss30% wt loss

⁄ 10% in Jan – 50% in 10% in Jan – 50% in Jul (Caswell, 1980)Jul (Caswell, 1980)

⁄ 50% loss in Ibadan, 50% loss in Ibadan, 30% in Zaria 30% in Zaria (Caswell, 1976(Caswell, 1976

0

25

50

75

100

Dec Jan Feb Mar Apr May Jun Jul Aug Sep

% damage

0

10

20

30

40

Number of farmers affected

Damage on stored cowpea in the Northern Region during the storage season 96-97

Unpublished Presentation

Control Control ““Medically harmless” when eatenMedically harmless” when eaten Crushed leaves of Crushed leaves of Cassia Cassia

occidentalis; occidentalis; oils from the seeds – oils from the seeds – inhibits growthinhibits growth

Biological control agents – Biological control agents – inshinda, parasitoid waspsinshinda, parasitoid wasps

Freezing storage area – -18ᶜ, Freezing storage area – -18ᶜ, 6-24hrs. Acclimitisation6-24hrs. Acclimitisation??????

Why safe cowpea from Why safe cowpea from beetlesbeetles

““Because of the quality of the cowpeas, Because of the quality of the cowpeas, you can add 20 percent to the price. We you can add 20 percent to the price. We are making more money.”are making more money.”

— — Balarabe Kausani, farmer, Balarabe Kausani, farmer, beneficiary of PICS Bag, beneficiary of PICS Bag,

Northern NigeriaNorthern Nigeria

““Today, livestock experts are drawn to the cowpea Today, livestock experts are drawn to the cowpea as they search for sustainable approaches to as they search for sustainable approaches to satisfying the fast-growing demand for meat and satisfying the fast-growing demand for meat and milk in developing countries. Scientists at IITA and milk in developing countries. Scientists at IITA and the International Livestock Research Institute the International Livestock Research Institute (ILRI) say new "dual use" cowpea varieties bred to (ILRI) say new "dual use" cowpea varieties bred to satisfy both human and animal nutrition needs satisfy both human and animal nutrition needs could be generating US$299 million to US$1.1 could be generating US$299 million to US$1.1 billion by 2020, given their potential to billion by 2020, given their potential to simultaneously boost livestock production and simultaneously boost livestock production and reduce hunger.”reduce hunger.”

- - Science Daily, 2010 Sep 27Science Daily, 2010 Sep 27

CONCLUSIONCONCLUSION Tiny though, Tiny though, C. maculatus C. maculatus has shown to has shown to be of significant consideration in be of significant consideration in the production, marketing and the production, marketing and consumption of consumption of V. unguiculataV. unguiculata: since : since it can destroy it both in the field it can destroy it both in the field and at storage, once it finds and at storage, once it finds choice dry beans. choice dry beans.

This pest is thus economically This pest is thus economically important as long as it is important as long as it is important to safe the cowpea from important to safe the cowpea from it and promote the booming of the it and promote the booming of the legume’s economy.legume’s economy.